Cortical actin filament organization in developing and functioning stomatal complexes of Zea mays and Triticum turgidum

Abstract

Cortical actin filament (AF) organization was studied in detail in developing stomatal complexes of the grasses Zea mays and Triticum turgidum. AF arrays during the whole stomatal complex development are dynamic, partly following the pattern of cortical microtubule (MT) organization. They also exhibit particular patterns of organization, spatially and temporarily restricted. Among AF arrays, the radial ones that underlie young guard cell (GC) periclinal walls, those that line the bulbous GC ends and the AF ring at the junction between subsidiary cells (SCs) and GCs are described here for the first time. Although many similarities in cortical AF organization exist among the stomatal cells of both plants studied, considerable differences have also been observed between them. Our data reveal that the expanding areas of stomatal cell walls are lined by distinct cortical AF aggregations that probably protect the plasmalemma against mechanical stresses. Experimental AF disruption does not seem to affect detectably stomatal cell morphogenesis. Moreover, the structural and experimental data of this study revealed that, in contrast to the elliptical stomata, in the dumbbell-shaped ones the AFs and MTs seem not to be involved in the mechanism of opening and closing of the stomatal pore.

The Type IIArabidopsisFormin14 Interacts with Microtubules and Microfilaments to Regulate Cell Division

“…It is well accepted that the microfilament cytoskeleton is strongly linked to these microtubule structures during cell division, although subtle differences in microfilament distribution have been identified (Panteris, 2008). While some studies have shown that microfilaments codistribute with microtubules in the preprophase band (Kakimoto and Shibaoka, 1987;Palevitz, 1987;Traas et al, 1987;Zachariadis et al, 2001Zachariadis et al, , 2003, others have shown that cortical actin filaments do not always follow the pattern of the preprophase microtubule band Wick, 1990, 1991;Panteris et al, 1992Panteris et al, , 2007Collings and Wasteneys, 2005). In the mitotic spindle, microfilaments are usually present (Schmit and Lambert, 1987;Seagull et al, 1987;Traas et al, 1987;Lloyd and Traas, 1988;Panteris et al, 1992;Cleary, 2001;Collings et al, 2001), but their absence from the spindle has also been reported (Liu and Palevitz, 1992;Baluska and Hasenstein, 1997;Vitha et al, 2000;Voigt et al, 2005).…”

Auxin as an inducer of asymmetrical division generating the subsidiary cells in stomatal complexes ofZea mays

“…This protein also accumulates at definite regions of subsidiary cells and intervening cells of stomatal rows of Z. mays, 57,58 where distinct AF accumulations have also been found. 34,58 Thus, the AF-patches at the polar end of Z. mays SMCs, should not be considered as prime polarizing factors, since they are absent from SMCs in other grasses like Triticum turgidum, but they may be related to the local SMC bulging toward the inducing GMC. 12,34 Evidence favoring this hypothesis is that in TIBA-and LY294002-treated SMCs, where the polar nucleus migration and the asymmetrical division were inhibited, AF-patches were assembled.…”

“…34,58 Thus, the AF-patches at the polar end of Z. mays SMCs, should not be considered as prime polarizing factors, since they are absent from SMCs in other grasses like Triticum turgidum, but they may be related to the local SMC bulging toward the inducing GMC. 12,34 Evidence favoring this hypothesis is that in TIBA-and LY294002-treated SMCs, where the polar nucleus migration and the asymmetrical division were inhibited, AF-patches were assembled. Moreover, in auxintreated leaves, in which SMC polarization and asymmetrical division is expanded into protodermal regions close to leaf base, AFpatch was only detected in SMCs bulging toward their adjacent GMCs.…”

“…2,12,34,59 The driving force generating such local mechanical stresses might be originated by the unequal elongation rates between the GMCs, the SMCs and the intervening cells of stomatal row. In particular, the lateral GMC cell wall seems to elongate more intensely than its SMC wall partner and the proximal to the GMC cell wall regions of the intervening stomatal row cells (unpublished data).…”

“…Actin filament staining Visualization of AFs was achieved using the procedure described previously in Panteris et al 34 Leaf strips of control and treated seedlings were incubated for 30 min in dark with 300 mM m-maleimidobezoyl-N-hydroxysuccinimide ester (Sigma) in PEM containing 2% (v/v) dimethyl sulfoxide and 0.1% (v/v) Triton X-100. The strips were then prefixed with 1 % (w/v) paraformaldehyde in PEM for 20 min and fixed with 4% (w/v) paraformaldehyde for 1 h. Afterwards, they were washed with PEM and extracted with 5% (v/v) dimethyl sulfoxide and 1% (v/v) Triton X-100 in PEM for 20 min.…”